Datacache and isolation level and advice

[killbulle <ma...@gmail.com>]

Not an easy subject..
as an old hibernate user i found a good link for the isolation level and the
second level cache
http://clustermania.blogspot.com/2009/07/with-read-write-hibernate-2nd-level.html
and as a new openJPA user and fan, i ask myself if the datacache implements
similar mecanism to warranty some consistency
Regards
Marc
NB(i plan to read the code:), but this is a tricky part)
-- 
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Re: Datacache and isolation level and advice

[Kevin Sutter <kw...@gmail.com>]

Hi Marc,
OpenJPA's 2nd level cache is more of a look-aside cache.  We use it to help
circumvent unnecessary trips to the database  The cache interface is not
transactional (yet).  That is, OpenJPA runtime determines when to "commit"
or "rollback" the contents of the cache.  Supporting a transactional
interface is not requirement of the cache plugin.  The cache contents are
kept consistent based on the locking mechanisms used to access the
Entities.  Much of this consistency is based on the optimistic locking
paradigm.  There is a chance of getting stale data, but attempting to commit
stale data will be detected during the optimistic version checking.
Stronger locking mechanisms (such as pessimistic) will bypass the cache and
work directly with the database to ensure consistency.

OpenJPA does allow for a pluggable cache implementation.  We provide our own
internal implementation, which performs quite well.  But, we also support an
EHCache plugin and a WebSphere Extreme Scale plugin.

More information on OpenJPA's 2nd level cache can be found here:
http://openjpa.apache.org/builds/2.0.0/apache-openjpa-2.0.0/docs/manual/manual.html#ref_guide_cache

Kevin

On Wed, Aug 25, 2010 at 3:58 PM, killbulle <ma...@gmail.com> wrote:

>
> Not an easy subject..
> as an old hibernate user i found a good link for the isolation level and
> the
> second level cache
>
> http://clustermania.blogspot.com/2009/07/with-read-write-hibernate-2nd-level.html
> and as a new openJPA user and fan, i ask myself if the datacache implements
> similar mecanism to warranty some consistency
> Regards
> Marc
> NB(i plan to read the code:), but this is a tricky part)
> --
> View this message in context:
> http://openjpa.208410.n2.nabble.com/Datacache-and-isolation-level-and-advice-tp5463092p5463092.html
> Sent from the OpenJPA Users mailing list archive at Nabble.com.
>